The present invention relates to the field of laser surgical instruments for use in optical surgery. More particularly, the present invention relates to a device that uses laser light to ablate ocular tissue, while at the same time minimizing potential damage to the eye during surgery by providing a structure which is capable of trapping laser light used in the surgical procedure.
The eye has an anterior chamber and a posterior chamber which are separated by a normally transparent lens. The lens is a clear tissue located behind the pupil. The lens works with the transparent cornea, which covers the eye""s surface, to focus light on the retina at the back of the eye. The lens of the eye is clear at birth, but is one of the first parts of the body to show the effects of aging. If the lens becomes cloudy, light cannot pass to the retina properly and vision is blurred and decreased. This clouding of the lens is known as a cataract.
As the lens becomes increasingly cloudy, light rays are prevented from passing through the lens and focusing on the retina. Early lens changes may not disturb vision. But as the lens continues to change, several specific symptoms may develop including blurred vision, sensitivity to light and glare, increased nearsightedness, or distorted images.
Cataracts are the leading cause of vision loss among adults age 55 and older. The most common cause of cataracts is aging. However, cataracts can affect all ages because they can result from injury, heredity, chronic eye disease, or system-wide diseases such as diabetes.
Sometimes, the cataract stops developing in its early stages, and vision is only slightly decreased. But if it continues to develop, vision is impaired, and treatment is necessary. Surgery to remove the cataract is the only effective treatment.
Cataract surgery has been practiced over a long period of time. In the earliest known technique the cataract was displaced to lie in the vitreous cavity in the back of the eye. Other ancient techniques included breaking up the cataract with a needle to facilitate absorption by the body, and removing the lens from the eye by applying pressure. The displacement or removal of the lens enabled the patient to see better. However, vision was still blurred because the patient lacked a lens to focus light.
In modern cataract surgery the cataract is extracted from the eye. In most cases the lens is replaced with a foldable lens implant inserted into the capsular bag. The lens unfolds within the bag during the surgical procedure in order to replace the natural lens taken out. With the insertion of the replacement lens, the patient is able to focus light as well as benefitting from the removal of the cataract. Thus, vision can be effectively restored to a normal state.
Cataract surgery has become quite common in the United States and other nations. The increasing incidents of cataract surgery has been due in part to the development of improved surgical instruments and techniques. Some of the improved instruments include the operating microscope with coaxial illumination. In addition, surgical instruments have been developed which provide simultaneous irrigation and aspiration for use in closed eye microsurgical systems. It will be appreciated that fluid pressure must be maintained within narrow limits in order to avoid damage to the eye. Therefore, devices which provide both aspiration and irrigation have been an important advance in ocular surgery.
Instrumentation of this type can operate through a small incision in the eye. Typically the incision is approximately 3-4 mm in length. Using this type of instrumentation cataract surgery is performed in which the cortical material of the lens is aspirated. However, the hard nucleus of the lens must be fragmented first and then aspirated.
One device which fragments the cataract is called a phacoemulsifier. This type of device uses an ultrasonically driven vibrating needle as a means of breaking up the cataract. A liquid flows to the surgical site and is aspirated along with the lens fragments. Although phacoemulsification is an improvement over earlier methods because it can be performed through a small incision, the surgical procedure is difficult and requires highly specialized surgical skills. In addition to the need to carefully control fluid flow through the surgical site, the heat and the vibration of the ultrasonic needle can damage adjacent ocular tissue. Clearly heat and vibration must be carefully controlled during the surgery. Thus, this technique has been found to be less than ideal and improvements in technique and equipment have been sought.
With the advent of the surgical laser, lasers have been adapted for use in ocular surgery. It has been found that the use of lasers in cataract surgery has somewhat alleviated the problems of ultrasonic phacoemulsification. With the use of lasers it is possible to construct the hand piece such that it is less bulky and more easily manipulated by a surgeon. This allows more surgeons to gain skill sufficient to manipulate the laser devices. At the same time, the laser does not create sonic vibrations that may cause damage to other tissue so that the risk of damage to the eye is reduced. Finally, there is less heat generated in the eye with the laser devices.
Even though the use of lasers in ocular surgery represents a large advance, there are still problems which arise. While heat and vibration are reduced over that experienced in ultrasonic phacoemulifiers, laser devices have the potential of damaging surrounding tissue through the generation of excess heat or release of deflected light and misdirected high energy laser beams. One problem arises from the fact that as laser light exits an optical fiber, the beam is dispersed. This stray light and other laser light that passes through the target tissue unabsorbed will continue beyond the surgical site. Such light, especially since it is generated by a relatively high powered laser, has the potential of damaging the eye and other tissues if not contained.
Attempts to control stray reflected light and misdirected laser beams have been largely ineffective. Traditionally, the control of misdirected light relies on the skill of the surgeon, not on any specific features designed into the surgical instrument.
In recent years laser surgical devices have been developed which attempt to control the passage of the laser beyond the surgical site. One such device has included a tip which extends distally from the point at which laser light is delivered to the surgical site. The tip extends outwardly and then turns upwardly such that it meets the laser beam exiting the fiber optic. In this manner, the laser beam is deflected such that the full strength of the laser beam does not pass beyond the surgical site. Even in this type of device, however, there is a danger of reflected or disbursed light causing damage, in that the tip of the device simply reflects and disburses the laser beam and provides no means to capture the light. Furthermore, at certain energy levels, the laser light can damage the reflecting tip itself.
Another deficiency of the prior laser devices relates to the configuration and positioning of the irrigation, aspiration, and laser systems. It will be appreciated that it is difficult to simultaneously deliver laser light and fluid to a surgical site, while at the same time providing fluid aspiration from the site. In certain device configurations, these functions can actually oppose one another. In such systems the various functions work against the other requiring more energy to break up the lens. At the same time, difficult design problems are presented in delivering the necessary functions to the surgical site in a manner that is easily controlled and directed by the surgeon. Existing systems are generally less than ideal in that regard.
Accordingly, it would be an advancement in the art to provide a surgical device which began to overcome the problems identified above. In particular, it would be an advancement in the art to provide a laser surgical handpiece which was capable of efficiently delivering laser light, irrigation, and aspiration to the surgical site. It would be a further advancement in the art to provide such a handpiece which included a structure capable of minimizing dispersed laser energy and reflected light beyond the surgical site. It would also be an advancement in the art to provide such a device which would collect stray laser light and remove the energy from the eye, and that would use irrigation and suction to complement the action of the laser. It would be an advancement in the art to provide such a laser surgical device which could be easily manipulated by a surgeon.
Such a device is disclosed and claimed below.
The present invention relates to the field of laser surgical instruments for use in optical surgery. More particularly, the present invention relates to a device that uses laser light to ablate ocular tissue, while at the same time minimizing potential damage to the eye during surgery. The present invention provides a laser surgical device for removal of intraocular tissue and specifically the removal of cataract lens tissue.
The device of the present invention includes a handpiece. The handpiece is sized and configured in much the same manner as conventionally accepted laser surgical handpieces. On the proximal end of the handpiece are the necessary connections and ports to run the device. These include a connection for receiving a laser beam generated by an external surgical laser of the type generally used in the field of ocular surgery. The laser connection in turn connects to an optical fiber which is capable of carrying the laser beam distally through the handpiece.
The handpiece also includes irrigation fluid and aspiration connections. Once again, these connections are similar to known devices and use conventional Luer connections. These connections are in turn in fluid communication with an aspiration channel and an irrigation channel which runs through the interior of the handpiece.
In certain preferred embodiments of the invention, the handpiece is configured to be of the same general size and shape as other optical surgical instruments within the same class. Thus, surgeons using the device will be generally comfortable with the device and understand its general methods of use.
Importantly, the invention includes a unique and inventive probe attached to the distal end of the handpiece. The probe is configured such that it conveniently and precisely delivers laser energy to a defined surgical site. The probe also provides precise fluid irrigation of the surgical site, as well as controlled aspiration of ablated tissue and fluid. In this manner, the surgeon is able to perform delicate and precise procedures while at the same time controlling the important functions of laser delivery, fluid delivery, and aspiration. Within the probe is a laser delivery structure. The laser delivery structure is an optical fiber or similar light conveying means. The laser delivery structure is capable of conveying a pulsed laser beam. Within the probe, the optical fiber is encapsulated to prevent the unwanted release of laser light. Generally, for surgical uses of the type discussed herein, the wavelengths of the laser will be in the range of from about 400 nm to about 3,000 nm.
In one important aspect, the probe of the present invention has a generally ski tip-shaped distal tip. The tip is formed so that it curves up to intersect the laser light emitted from the optical fiber. The tip contains an aspiration inlet in the face of the tip. The tip is also configured such that it functions as a xe2x80x9cphoton trap.xe2x80x9d That is, to the extent that laser light passes from the end of the optical fiber and through the region in which surgery is performed, the light intersects the tip and is collected. In one presently preferred embodiment, the photon trap and the aspiration inlet are formed by a single hole in the tip which is directly in the path of the pulsed laser bean The photon trap is configured so that any percentage, including all, of the laser light passing beyond the surgical site is collected. While the percentage of light collected may be varied depending on the size and placement of the photon trap, it is preferred that the photon trap be configured for the present application such that at least about 40% of the light is collected. More preferable, the tip is configured such that at least about 75% of the laser light is absorbed and collected without being reflected. As a result of the efficient collection of the laser light, any excess heat produced by the laser light is largely absorbed by the photon trap and aspirated out of the surgical site with the irrigation fluid. The photon trap redirects the collected laser light to further emulsify the ablated tissue particles once they enter the aspiration channel.
Also within the probe is an irrigation channel which in one preferred embodiment is formed from a sleeve formed by the exterior walls of the probe. The irrigation channel has one or more openings near the distal end of the probe creating a fluid outlet that allows irrigation fluid to flow into the surgical site. The distal end of the probe is tapered and mates with the irrigation sleeve to prevent unwanted leakage of irrigation fluid. Thus, irrigation fluid is conveniently provided to a point near the surgical site. Because of the operation of the aspiration channel, the fluid flows out of the irrigation openings and into the surgical site.
As mentioned above, the probe also has an aspiration channel This channel is disposed within the body of the probe and continues onto the tip. At the tip there is an aspiration inlet which may correspond to the photon trap. A vacuum is applied to the aspiration channel in the manner conventional in that art. Thus, the tip allows the irrigation fluid and ablated tissue to be removed from the surgical site.
The irrigation channel and the aspiration channel are positioned so that they create a xe2x80x9cclosed loopxe2x80x9d irrigation system. This system draws target tissue near the tip and directly in line with the path of the pulsing laser. Placing these structures in line with each other produces a synergistic effect where the action of the laser pulses and the suction and irrigation complement each other. In this manner, the target tissue is ablated and drawn out of the surgical site. Furthermore, the configuration of the system allows heat associated with the laser surgery to be conducted away from the surgical site by the aspirated fluid flow.
In certain preferred embodiments of the device, the laser delivery structure, the fluid delivery channel, and the aspiration channel are disposed of coaxially in the body of the device. This allows each of these functions to be made available in a controlled and efficient manner.
It will be appreciated that the probe is attached to a handle for manipulation of the probe by a surgeon. As mentioned above, the handpiece as a whole is configured and designed such that it is similar in size and shape to other similar types of surgical devices. The optical fiber running through the handpiece to the probe is attached to an external laser system This attachment is made by a conventional fiber optic attachment. The aspiration and irrigation systems of the device are also attached to an external fluid source and an external vacuum source. These attachments are made by means of conventional Luer connections. Generally, the surgeon will control the laser, aspiration, and fluid flow by means of a conventional foot pedal apparatus, such as those widely used in ocular surgical procedures. Thus, the flow of fluids and the delivery of laser light is carefully controlled by the surgeon.
Thus, it will be appreciated that the present invention provides a laser surgical handpiece which is capable of efficiently delivering laser light, irrigation, and aspiration to the surgical site. The device also inimizes dispersed laser energy and reflected light beyond the surgical site. The device provides a photon trap structure which collects a significant percentage of any stray laser light.
The above described and other features and advantages of the present invention will become more fully apparent through the following detailed description and drawings, taken together with the appended claims.